Installation has finally begun on Jeff Bezos' 10,000-year clock, a project that the Amazon CEO has invested $42 million in (along with a hollowed-out mountain in Texas that Bezos intends for a Blue Origin spaceport), with the goal of building a mechanical clock that will run for 10 millennia.

The actual idea for the clock comes from Danny Hillis, who originally proposed a 10,000-year clock in 1995 in Wired as a way to think about the long-term future of humanity and the planet. That idea grew into the Clock of the Long Now, a project by the Long Now Foundation, which Hillis went on to co-found to build an actual, working version of the proposed clock.

The group built a couple of prototypes, but Bezos' clock — which Hillis is designing — will be the first to function on a full scale. The team has spent the last few years machining parts for the clock and drilling through the mountain to store the components. Bezos announced today in a tweet that installation of the machinery has begun on the 500-foot-tall mechanism.

According to the website for Bezos' 10,000-year clock, visitors will (in theory) be able to view the finished timepiece, although the site notes that it'll be a rough trip. "The nearest airport is several hours away by car" and a rugged foot trail that rises almost 2,000 feet above the valley floor.